Electric heater



Feb. 16,1943.

ELECTRIG'HEATER Filed June' 15, 1940 I 2 Sheets-Sheet l- 5 BY I 2MAKORNEY E. c. CROWLEY 2,311,371

w v .T QQQQQ P Feb. 16, 1943. E. c. CROWLEY ELECTRIC HEATER Filed June13, 1940 Patented Feb. 16, 1943 UNITED STATES PATENT OFFICE ELECTRICHEATER.

Edward Chase Crowley, Rhinebeck, N. Y.

Application June 13, 1940, Serial No. 340,288

10 Claims.

This invention relates to electric heaters and more particularly toelectric resistance wire supports and surrounding structures.

The objects of this invention are to provide an improved electricheating unit of the closed type in a three dimensional self supportingframe structure of low thermal mass with hollow bays therein, throughwhich resistance wires pass in protected formation, and with appropriateopenings in walls of these bays for the emission of heat from saidresistance elements, and in some cases for the passage of drippingstherethrough.

Further objects of the invention are to largely confine the conductionof heat to the article or surface desired to be heated; to provideimproved electric stove structure; to provide refractory pieces whichare readily formed and easily applied; to provide an improved skeletonframe for both forming said bays and for mounting the refractory piecesfor the resistance heating element; to provide a skeleton framestructure of rigid characteristics and minimum heatabsorbing mass; toprovide a skeleton frame structure which both carries the refractorypieces and constitutes the utensil-supporting grid and is itselfsupported from below; to enable the skeleton frame to be fabricated insec tions; to adapt the structure to utilization of strip metal or flatwire or ribbon for the said frame; to provide a structure which isapplicable to oven structure as well as to top-of-the stove structure;to secure simplicity of construction and operation; and to obtain otheradvantages and results as may be brought out in the followingdescription.

In the accompanying drawings in which like numerals of referenceindicate similar parts throughout the several views:

Figure 1 is a plan of a two burner stove structure embodying myinvention with certain parts broken away and one skeleton frame inhorizontal section;

Figure 2 is a longitudinal Vertical section substantially on line 22 ofFigure 1;

Figure 3 is a transverse sectional view substantially on line 3-3 ofFigure 1;

Figures 4 and 5 are perspective views of skeleton frame sections, whichwhen assembled constitute the skeleton frame;

Figure 6 is a perspective view of one of the refractory pieces;

Figure '7 is a perspective view of a portion of parallel walls of theskeleton frame ready to receive one of the refractory pieces;

Figure 8 is a perspective view of a portion of two of the parallel wallsof the frame, similar to Fig. '7, showing a slightly modifiedconstruction;

Figure 9 is a perspective view of structural elements utilized inadapting the invention to use in an oven;

Figure 10 is a sectional plan of a portion of the oven structureassembly;

Figure 11 is a vertical elevation of my invention adapted to be used asa tubular heater; and

Figure 12 is a transverse sectional view of the same, on line I2l2 ofFigure 11.

Referring to the specific structure illustrated in Figures 1 to 6inclusive, where the invention is shown in connection with use as stovetop burners, the reference numeral 15 designates in general the stovebody here indicated as adapted for two units or burners. The particularstove body here shown comprises a rectangular hollow frame with uprightside and end walls and with inturned flanges next the tops thereof forconstituting the top surface it of the stove body, and with inturnedbottom flanges IS on the side and rear walls for resting upon asupporting surface. The burner units are situated within the open spaceprovided within the confines of the upper inturned flanges and in suchmanner that the tops of the burner units are substantially in the sameplane with said flanges. At one end, which for convenience will bereferred to as the back of the stove, the wall there situated isextended upwardly a suitable distance above the stove top It, in thenature of a splash board, and provides suitable means for supportingcurrent controlling switches I! in an suitable manner.

Spaced below the stove top It in a plane parallel thereto, are aplurality of fixed brackets I8, shown, for instance, in Fig. 3, as flatarches, that is, horizontal cross-reaches with downwardly bent endshaving outwardly extending feet resting upon the upper surface of thelower side flanges 16', with asbestos pads l8 interposed between saidfeet and flanges. The said crossreaches may be provided with hooked lugs[9 on their undersides and near the ends thereof for support of aheat-reflector 2i] hereinafter referred to, The upper sides of saidcross-reaches constitute rests or supports for the burner units.

The burner units each preferably are fabricated as skeleton frames,constituting a lattice work, with refractory pieces mounted therein forcarrying the electric-resistance heating elements. The skeleton frame isdesignated generally by numeral 2| and is preferably made up insectionsZl, 2 If which interfit and when assembled are secured togetherto constitute the complete frame. The sections shown separately in Figs.4 and 5, are fabricated each from strips of metal arranged edgewise andbent in the formation of triangular boxes, forming bays, with ahypotenuse between two opposite corners, and with the two hypotenuse ofthe two triangular bay formin boxes alined or in continuation one withthe other. The said hypotenuse extend beyond the contiguous corners ofthe two boxes and join the boxes by a short intervening portion of theextended hypotenuse between said boxes. Another pair of connectedtriangular boxes, also forming bays, adjoins the first pair with therespective hypotenuse of the first pair contiguous to the hypotenuse ofthe second pair, thus forming a pair of rectangu lar boxes with adiagonal 22 across each and with the diagonal of one rectangular boxalined with the diagonal of the other and with the rectangular boxescornerwise with respect to each other and connected by the extendedportions of said hypotenuse which accordingly constitutes an interveningportion 23 of the extended diagonal between the contiguous corners ofthe rectangular boxes. This connected pair of rectangular boxes, formingits several triangular bays, is herein referred to as a section 21 ofthe skeleton frame 2 I, and it will be observed two sections, one shownin Fig. 4 and the complement in Fig. 5 make up the said frame.

The said intervening portion 23 of one section, between and integralwith a pair of rectangular boxes, is notched upwardly from its underedge and the other intervening portion of the other section is notcheddownwardly from its upper edge, thereby enabling the two sections orpairs of rectangular boxes to be interfitted, so as to constitute thesymmetrical structure of rectangular skeleton frame, with its pluralityof triangular bays of which all the apexes are toward a common center,shown in Figure 1. Thus the diagonals of the several rectangular boxesconstitute complete diagonals for the larger rectangle of the skeletonframe. While the foregoing description has been specific to the showingof rectangles and triangles as the geometric shapes involved, the sameis done by way of explanation and not necessarily restrictive thereto,since it is within the scope of the invention to employ circular orother configurations for the skeleton frames and correspondingly alteredshapes of the components constituting the same.

By use of suitable means 24, such as screws, pins, bolts or the like,and situated for instance in corners of the frame, and projecting upwardfrom the brackets E8, the skeleton frames are centralized with respectto the opening in the stove top, preferably affording a gap or opening25 next the outer walls of the said frame which are contiguous to theinner edges of the flanges forming the stove top, The gap preventstransmission of heat by conduction from the skeleton frame to the stovebody or flanges It. The skeleton frame is thus isolated from contactwith the stove body and any loss of heat by conduction is limited tocontact of the skeleton frame with the brackets l8, and in a downwardpath, and is ultimately interrupted by the interposition of saidasbestos pads l8 next the bottom flange of the stove body.

Resting on the top edges of the skeleton frame walls is a plate 26, theupper surface of which is preferably in the same plane as the topsurface of the flanges or stove top it. Said plate constitutes the topwall for the several compartments of a unit. This plate may be,,as,

or opening 25 between its periphery and inner.

edges of the flanges, and thus prevents conduction of heat from theplate to the stove body or flanges It.

Returning now to detailed description of the skeleton frame in itsrelation to the electricresistance heating element, it is to be observedthat by the construction heretofore described, the diagonals are doublewalls which are, for the greater part of their lengths, offset toprovide a space 21 therebetween. Likewise, the contiguous walls of theassembled rectangles have the greater parts of their lengths ofiset toprovide similar spaces 21 therebetween. Thus. between all adjacent baysthe frame provides double or contiguous walls and said walls are, forthe greater parts of their lengths between bays, spaced and parallel ineach instance.

Two of the contiguous walls of the two sections 2i, 2|, and portions ofalined walls inte'rcepted thereby, are of less height, as indicated at28, than the remaining walls and/or portions of walls, so as to provideentry space and fan-like distribution .of lead-in wires 29 for thecurrent. The others of the contiguous walls than the ones just mentionedare recessed or notched downwardly from their upper edges, as at 36,with the notches of contiguous walls directly opposite each other.Refractory pieces 3| are provided which will span contiguous walls andsubstantially fill the notches. Tenons 32 project from the lowermid-portion of these refractory pieces, said tenons having a thicknessappropriate to substantially fit between said contiguous walls of theframe, and thus keep the refractory pieces from sliding transverse tothe walls out of the notches. Corresponding holes 33 in the tenons and34 in the walls beneath the notches may be provided if so desired, andin the absence of plate 26 then enable the refractory pieces to bepinned, bolted or otherwise retained in the notches.

As shown, each pair of contiguous walls provides a series of threenotches thereby accommodating a series of three refractory pieces foreach pair of contiguous walls, and the arrangement of walls being suchthat they cross or emanate from a common center, the refractory piecesat corresponding distances from that center will be situated on ordefine points of circles about that center. The several refractorypieces have holes 35 therethrough in directions perpendicular to therespective walls where situated. Obviously a single refractory piecehaving three holes 35 therein may be used by merging said three notches38 into one continuous notch. Passed through these holes 35 areelectric-resistance heater-elements 36, preferably one for each of thesuccessive circular series of refractory pieces. Each heater element,being passed through the refractory pieces at equal distances from thecenter, assmnes an arcuate shape and by terminating both ends thereof inthe vicinity of the part of the skeleton frame having the lower wall,appropriate connection can be made with the leadin wires situatedthereat. Part of each heating element passes through each bay, so nomatter which element is heated, each bay is affected.

The electric-resistance heater elements are each shown, by way ofillustration, as of helical formation, and are exposed in all directionswithin the bays to the walls thereof. Each element is likewise anindividual heating unit usable alone or in combination with one or moreof the other elements. By way of example, the innermost element may be,let us say, 250 watts,

the middle element 500 watts and the outermost element 750 watts.Accordingly, by use of one element alone, or combinations of elementsoperating simultaneously, a variety of heats may be accomplished byelectric consumption of 250 watts, 500 watts, 750 watts, 1000 watts,1250 watts or 1500 watts. Each heating element is connected individuallythrough a separate one of the switche ll, thereby enabling the user tomanually throw the desired one or combination of heating elements intouse at will.

The above description makes it apparent that the heating elements aresituated within the severals bays between the upper or stove-top plate26 and the under or reflector plate 29, which accordingly constitute thetop and bottom walls of said bays. Both of those plates are preferablyof relatively small mass so as to have minimum heat-absorbing capacity.Furthermore, said upper and lower plates are both provided with aplurality of arcuate slots or other openings El, 38 respectivelytherein, situated to have corresponding positions one above the otherand offset from the heater elements, that is, so that the arcuate slotsor openings of the upper plate are directly over the arcuate slots oropenings of the lower plate, and with no part of the heater elementdirectly between opposite upper and lower openings. The heaterelementsvare, on the other hand, directly between respective opposedsolid portions of the plates and thus protected by those solid portionsfrom drippings which are free to pass directly through the openings.Beneath the lower plate, here shown slidably resting on lower flanges l6of the stove body, is a drip pan 3%, somewhat larger than the said underplate. As the drippings will thus pass through the reflector plate, saidplate may be retained clean and brilliant for maintaining maximumefficiency for heat refiection. Suitable means, such as downwardlypressed ribs 40 in the reflector engaging the hooked lugs 19, may beprovided for positioning the under or reflector plate 20, enabling saidplate to be also conveniently removed for cleaning and returned toproper place. The upper or top plate 26 is likewise removable forcleaning purposes and is shown provided with a depending peripheralflange H so it may be replaced and retained from lateral dislocation inuse. The construction is accordingly such that the stove top may beutilized for visible broiling purposes.

The refractory pieces are preferably restrained from upward removal bythe situation of top plate 26 thereover. Said top plate has its uppersurface in a plane with the top surface of stove top flanges without anyprotuberances, and thus cooking utensils may be slid from place to placethereon without having to be lifted or suffering interference. Therefractory pieces are made as small as practicable, and are actuallysmaller than would appear from the drawings, where, to clearlyillustrate walls, increase of thicknesses of the showing was necessary.In actual construction, a far greater proportion of heating element ofeven the inner element is exposed than is covered by or included withinthe refractory pieces. Furthermore, the holes through the refractorypieces flare at opposite ends so that there is minimum contact ofheating element with the refractory pieces and heat will readily emanatefrom around the heater out of said holes.

In actual manufacture the refractory pieces are given a dimensionlengthwise of the holes for the heating element very slightly largerthan the distance from the outside faces of the parallel wallssupporting the same. Said pieces are each formed with shoulders next thetenon so as to rest on the corresponding edges of the notches of thewalls. However, if desired, and as indicated, in Figure 8, the bottomedge of the notch may be formed by bending of all or part of the metalstamped from the notch into a horizontal or shelflike position, as at42. Such structure has the advantage of increasing the rigidity of thewall as well as increasing the area of supporting engagement with therefractory piece.

For purposes of adapting the invention to oven structure, a skeletonframe 43 is illustrated in Figure 9 providing a horizontally disposedbottom frame section 44 substantially coextensive with the bottom areaof an oven, and upright frame sections &5, 45, from the sides of thebottom section. These several sections are constructed from strips orribbons of metal with portions theero-f parallel and closely spaced toconstitute parallel walls 46 for reception of the aforementioned tenonsof the heretofore described refractory pieces. These walls 46 arenotched at 41, as before, to receive the refractory pieces in thenotches. A heater-element preferably of helical construction aspreviously described, is passed back and forth on a path a indicated bydot and dash lines 48 to make series connection with a pair of prongs19, 49 at the rear of the bottom section 44. These prongs will entersuitable sockets (not shown) for completing electric circuit connectionwhen the frame is slid home in the oven, such circuit of course includinan appropriate switch (not shown) for manipulation by the user. Anappropriate top plate 5f: i provided to seat between and face the sideframe sections and to seat upon and face the bottom frame section. Thistop plate has runways 5! for the usual oven grill or shelf. Runners 52are provided beneath the skeleton frame as part thereof said runnersbeing wide enough to receive bolts, rivets or the like entering both thebottom section and side sections for holding said sections assembledwith respect to each other, and the top plate likewise is flanged atfront and back and adapted to be held by part of said bolts passingtherethrough. The runners extend from front to back next the sides andenable the skeleton frame and plate to be removed as a unit from theoven. The top plate has suitable slots 53 therein offset in dispositionfrom directly overlying the heater element.

The disposition of the heater element in the side frame sections as wellas in the bottom section affords quick heating and distribution of heatin the oven. Fabrication of the frames from strips, bent back and forthand, for each section, included Within a peripheral enclosing framepiece to which they are welded or otherwise secured, adds to simplicityof construction from a minimum number of parts, obtains unit parts fewin number and rigid in character. In both this construction and thestove-top construction previously described, the vertical disposition ofthe parallel walls affords a rigid support for cooking utensils withemployment of lightweight or thin-gauge metal, and this minimizes themass and conduction characteristics of the skeleton frame. A reflectorplate 20 may be provided, as indicated, beneath the bottom skeletonframe section and at the outside of the upright sections. The bottomportion of thi reflector plate has openings 38' therein directly belowthe openings or slots 53 of the top plate and thus will permit drippingsto pass directly through.

As indicated in Figures 11 and 12, the invention is also applicable touse with heater elements for tubular heaters, such as are employed fortank or water heaters. In said figures, a plurality of pairs of parallelclosely spaced walls 54 are provided. These pairs of walls are shownlongitudinally disposed as a circular grouping so that two of the pairsare diametrically opposite and the other two pairs While alsodiametrically opposite to each other are in a diametric plane normal tothe similar diametric plane of the first pair. The outer edges of all ofthese walls are notched inward, as at 55, to receive the refractorypieces previously described, and the walls are spaced properly, asbefore, to receive the tenons of those pieces. The notches are alsoproperly positioned lengthwise of the walls to accommodate a spiraldisposition of the heater element 56. Said heater element is againpreferably a helical coil of suitable electrical capacity.

The refractory pieces are held in place in the notches by band-likeframes or plates 51' extend ing lengthwise of and normal to the parallelwalls and connected in pairs at top and bottom ends of said walls. Thestructure is therefore one which enables the skeleton frame, with plates51 applied thereto, to be handled and manipulated as a unit, andinserted as such into the tube 53 forming part of the water heater orsimilar device. The metal used in each case for the notchedrefractory-element supporting wall is preferably strip metal generallyknown in the trade as flat wire or ribbon, and possesses the desiredthin-gauge characteristic.

Obviously other detail changes, modifications and uses may be made thanthose here specifically illustrated and described, without departingfrom the spirit or scope of the invention, and I do not wish to beunderstood as limiting myself to the details of disclosure except as-setforth in the following claims when construed in the light of the priorart.

I claim:

1. An electric heating unit comprising a skeleton lattice-work frame,insulator elements with transverse bores therein supported in spacedapart relationship in said frame, and an electric heating elementdisposed throughout said frame and threaded through and supported insaid bores in said insulators, said skeleton latticework frame beingcomposed of sections of strip material disposed both to constitute saidframe and to form in said frame substantially parallel, narrowlyspaced-apart, two wall supports for said insulator elements withparallel notched openings in said two walls, and said insulator elementsconstituting a bridge for said bore between and across both of said twowalls and fitting snugly in said notched openings and between saidwalls.

2. An electric heating unit as set forth in claim 1, wherein saidinsulator elements are substantially rectangular in shape with a boreextending transversely therethrough and wherein said insulator elementsare narrowed in cross section in the lower part thereof to provide tworabbeted shoulders and a projecting tenon so that said rabbetedshoulders must both bear upon the notched portions of said two wallsupports, with said transverse bore extending between and beyond thenotches in said two wall supports, with said projecting tenon disposedin snug fit in the space between said two wall supports below saidnotches.

3. An electric heating unit as set forth in claim 1, wherein saidinsulator elements and said notched two wall supports have correspondingopenings for receiving locking pins for holding the insulator elementsin assembled relation with said wall supports.

4. An electric heating unit such as set forth in claim 1, wherein thesaid unit has an exterior casing, a part of which is formed by part ofsaid skeleton lattice-work frame as herein described.

5. An electric heating unit such as set forth in claim 1, having a heatreflector spaced from said lattice-work to reflect radiant heat to andthrough said lattice-work as herein described.

6. An electric heater providing a detachable electric heating unithaving bare resistance elements, a metal casing in hollow formation inspaced relation to and surrounding and protecting said resistanceelements on all sides, ceramic buttons supporting said resistanceelements at intervals of the length of said elements, metal strips whichform part of said casing and also form an independent three dimensionalskeleton metal frame support for said ceramic buttons and resistanceelements, said frame holding the ceramic buttons and resistance elementsin spaced-apart relationship to each other and to said casing, said unithaving for the top and bottom walls of its said casing separatelydetachable metal plates having alined openings therein, said resistorelements being offset from alignment of said openings.

7. An electric heater having heating unit as described in claim 6 andhaving its said top plate together with any objects placed thereonsupported by said frame and having its bottom plate constituting areflector plate horizontally detachable while the unit remains inoperation.

8. An electric heater having a heating unit as described in claim 6disposed in a frame and having supports disposed at the bottom of theunit interposed between said unit and said frame and supporting saidunit in a completely isolated position within and completely out ofcontact with said frame, and heat conduction insulating means interposedbetween said support and frame, whereby the unit is supported free fromheat-conducting physical contact with the said frame.

9. An electric heater in accordance with claim 6 disposed in a frame andwherein said top detachable plate of the heating unit has its uppersurface in the same plane as the upper surface of the top wall of thesaid frame.

10. An electric heater in accordance with claim 6 disposed in a frameand wherein said top detachable plate of the heating unit has its uppersurface in the same plane as the upper surface of the top wall of thesaid frame, and wherein a peripheral gap is provided around said topplate and the said top wall of the said frame for heat-insulatingpurposes.

EDWARD CHASE CROWLEY.

